Abstract: This study compared gill monogenean parasite of Tylochromis jentinki from two sectors in Ebrié lagoon during March 2017 to February 2018. Six hundred specimens of T. jentinki were necropsied for parasitological analysis. Gills were prepared from each specimen following standard methods for microscopic analysis. Parasitological indices were calculated. The diversity indices were determined using Berger-Parker dominance index, Shannon-Weaver index, Pielou’s measure of evenness, Margalef’s diversity index and the Simpson index. Three species (Cichlidogyrus berrebii, C. kothiasi and C. pouyaudi) occurred and the parasitic populations varied depending on the sampling sector. All the indices considered showed significant differences among the two sectors of Ebrié Lagoon except for the evenness which showed no significant differences both study areas. The diversity of monogenean seemed to be influenced by environmental conditions.